[MERGE] Try harder to avoid loading plugins during the test suite.

[Ian Clatworthy]

Andrew Bennetts wrote:
> This is a bit of a band-aid.  I think maybe a deeper fix would be better.
> But in the meantime, here's a patch that fixes a few parts of the test suite
> that would inadvertently load plugins while running the test suite.

bb:tweak

> +        args = ['--no-plugins'] + args
>          self.log('run bzr: %r', args)

I'm really not comfortable with this line being unconditional.
I think it needs a guard something like ...

  if bzrlib.plugins.__path__ == []:

given the implementation of bzrlib.plugin.disable_plugins().

> +        out, err = self.run_bzr('--no-plugins help commands')
> +        print err

Delete the "print err" bit. :-)

Ian C.